A comparative study on the hemodynamic effects of initiating positive airway pressure treatment in patients with obstructive and central sleep apnea.

Purpose: Both obstructive (OSA) and central sleep apnea (CSA) are associated with considerable cardiovascular morbidity which argues for treatment initiation with a positive airway pressure (PAP) device even in the absence of significant day-time sleepiness. While the long-term consequences of PAP treatment in patients with sleep disordered breathing have been investigated in several studies, less is known about the immediate hemodynamic effects. Therefore, the present study intended to investigate the immediate effect of PAP treatment on non-invasively measured hemodynamic parameters in 10 patients with either OSAS or CSA.

Methods: During diagnostic and therapeutic conditions, the routine polysomnographic assessment was extended with an impedance cardiography (ICG) system. Statistical analysis was performed to find differences between both groups and conditions. In addition, the relationship between the treatment associated effect on stroke volume (SV) with biometric, polysomnographic, and cardiovascular parameters was assessed.

Results: Comparing both subgroups, we found statistically significant differences for biometric, polysomnographic, and cardiovascular parameters. Patients with CSA were older (p = 0.0005) and had higher values for diagnostic (p = 0.015) and therapeutic (p = 0.029) pulse pressure and the pre-ejection period under diagnostic conditions (p = 0.031). In contrast to patients with CSA who exhibited a slight increase of SV and derived parameters under therapeutic conditions, a pronounced decrease was observed in patients with OSAS which was statistically significant for the cardiac index (p = 0.038).

Conclusion: Our results indicate that patients with OSAS and CSA who are characterized by unique clinical features may show a distinguishable hemodynamic response to PAP treatment that can be measured non-invasively with ICG.